Specifically, it was the video's first part about how conquering, plundering, and stealing territory and resources is viable strategy for sustaining the economy of a pre-industrial society that's confined to a single world, where said world is a "zero-sum game" so to speak, but it apparently is a more inefficient and wasteful strategy for industrialized societies to engage in.

From there I applied that logic to more technologically advanced, futuristic societies, which in turn got me wondering about the Cardassian Union who tried that same strategy with Bajor, a multi-planet empire and a single-planet race respectively if I recall correctly, the former occupying the latter for its resources. My question is what could possibly be on a single, populated planet that any futuristic space empire with a replicator-based economy could want so badly that it's willing to engage in a decades-long occupation that's incredibly costly in both finances and manpower. Bajor is allegedly rich in natural resources which is what in turn attracted the Cardassians' attention in the first place, but I'd think that said resources would be available in far more abundance in space, on things like asteroids and barren worlds that don't inconveniently have technologically inferior but still-advanced populations to wage a long and bloody guerilla war against you the entire time you're there in retaliation for your needlessly brutal subjugation of them, and eventually make things so ruinous that the government has no choice but to pull out in face of political pressure.

So does that whole scenario make as little sense to anyone else as it does to me, or am I missing something here? Then again, even if it doesn't make much sense in the context of the setting, I figure it's not out of place among things like a race of technologically advanced yet medieval-minded Space Viking warriors like the Klingons, or a race of hyper-greedy Space Capitalists like the Ferengi. Therefore a race of totalitarian police state Space Imperialists who wastefully and brutally invade and occupy populated, developed planets because of reasons resources isn't much of a stretch. Star Trek practically runs on the Planet of Hats trope, after all!

--The Cardassians aren't as advanced as the Federation, so they may not have as many replicators and/or replicators may be more of a controlled resource for them.

--Part of the reason their government is a military dictatorship is they suffered a major collapse in their history where their planet became ecologically devastated due to over-exploitation (IIRC). This led to something like decades or centuries of a planetary depression, and much of their planetary wealth was sold and traded for resources.

--The Cardassians aren't as much of an empire as all that, IIRC they don't dominate any other sentient species other than the Bajorans and wildcat colonies that the Maquis came from. It may be that their Union is more a collection of colonized, otherwise uninhabited planets and moons, along with Cardassia Prime of course. For a sector power honestly they're not very impressive compared to say the Klingons or Romulans. This is part of why the Federation was able to more or less compel them to a treaty; they simply weren't strong enough to face the Federation on equal footing.

So, yes, essentially the whole justification was something along the lines of 'we need resources, Bajor is convenient to us, let us take it and exploit the heck out of it'. They're a small scale enough civilization that a planet is still a massive source of resources for them, particularly one that is already populated (a source of workers) and developed (already making use of planetary resources, minimal infrastructure construction required). Take, I dunno, smelting metal ore into refined forms; if the Cardassians took an undeveloped world, they'd have to go to a lot of effort to build facilities for that. On Bajor, the facilities are already there, and only require taking and using (minus any repair if sabotage occurred).

Non-canon, but in the Autobiography of Jean Luc Picard, the whole reason Cardassia fought the Federation was to obtain Replicator technology and territory for their starving industry and people. Bajor probably offset that cost with it's reaources and food.

Though it's also important to remember that the Cardassians weren't known for their efficiency, unless it came to stamping out dissent. And even with that, Cardassia had a full on Underground movement that came to a head in the 2370s.

On the one hand, Replicator tech seems like a very worthwhile goal to pursue. In fact, they even got it from the Federation eventually when they were so mauled by the Klingons that the Federation tried to aid their crippled infrastructure with "industrial replicators". On the other hand, why wouldn't they just try to buy them from the Ferengi or any other race that possesses it? Or simply have the Obsidian Order steal some plans? The technology seems to be extremely widespread among the space faring races.

No, I think the Cardassian Central Command was feeling their oats, saw how peaceful the Bajorans were, and decided to begin to build their glorious empire through conquest. And after annexing Bajor, they made a huge over-extension when going up against the nearby Federation and gassed their entire civilization out, where it was run over by the Klingons and later the Dominion.

"A person is smart. People are dumb, panicky, dangerous animals and you know it. Fifteen hundred years ago everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat, and fifteen minutes ago, you knew that humans were alone on this planet. Imagine what you'll know...tomorrow."
-Agent Kay

It's clear that the Cardassians and their society are imbued with a sense of superiority and efficiency. Their imperialist motives came from that ingrained desire to dominate the other person in the room, as Capt. Jellico alluded to in "Chain of Command". The fact that they were inferior in tech and power compared to others was not something that was easy to swallow -- add in the economic disaster they dealt with, and you have a very wounded collective ego. With that much pride, it makes sense that they would become even more devoted to establishing their superiority over whomever was in reach. The parallels to the gradual rise of the Nazis out of Germany's defeat in WWI become quite apparent -- humiliation and hardship can make you reassess your strategies or it can make you double down on the old ways.

My understanding of the Bajor situation is that they welcomed the Cardassians with open arms initially and gladly shared their knowledge and resources. The Cardassians saw them as an easy mark and steamrolled them when they had the opportunity. They didn't expect the Bajorans to retain such strength in their cultural bonds, their faith, and their thirst for freedom. Had they not been so arrogant and so set on conquering worlds rather than inviting them into their fold, they may have gone about their expansion very differently.

The great virtue of a free market system is that it does not care what color people are; it does not care what their religion is; it only cares whether they can produce something you want to buy. It is the most effective system we have discovered to enable people who hate one another to deal with one another and help one another. – Milton Friedman